Recognizing High Comorbidity of BPD and Bipolar Disorder Key in Treating Patients With "Borderpolar"

In the conclusion of this 2-part series, Mark Zimmerman, MD, director of the Partial Hospital Program and Outpatient Services at Rhode Island Hospital dives into the current research and research gaps surrounding "borderpolar" as well as the importance of diagnosing and treating both comorbid disorders. The term "borderpolar" refers to patients with both borderline personality disorder (BPD) and bipolar disorder.

"It's important to recognize that, with respect to borderline personality disorder and bipolar disorder, it's not an either/or selection or choice that needs to be made, that [a] not insignificant number of individuals have both disorders, and that when both disorders are found to be present, it's important to treat both pharmacologically and psychotherapeutically," says Dr Zimmerman.

In the previous Part 1, Dr Zimmerman, who was recently featured in People discussing the term that was originally brought to the Psych Congress audience in 2019, urges colleagues to recognize "the fundamental treatment of these 2 different disorders is quite different" and that "borderpolar" is a term, not a diagnosis.

Dr Zimmerman is interviewed by Psych Congress Network's associate digital editor, Meagan Thistle.

Meagan Thistle: So, you went into the literature a little bit, but is there any other research that's coming out about treatment options or anywhere else that you see a gap in the research?

Dr Mark Zimmerman: Oh, well there's a tremendous gap in the research. To illustrate, not necessarily with borderpolar, but just borderline personality disorder and major depressive disorder. There are no studies, no controlled pharmacotherapy studies of individuals with that comorbidity, and yet medication is routinely prescribed for individuals with borderline personality disorder and major depressive disorder.

And if you look at official treatment guidelines, they vary in their recommendations, but most will suggest that you should use antidepressants to treat the depression, though there's no research to support that. There are no studies demonstrating that the use of antidepressants in individuals with both major depression and borderline personality disorder effectively treats the depression.

And that's with major depressive disorder. You can imagine that there's practically no data, I'm only aware of one controlled study of medication for individuals with both borderline personality disorder and bipolar disorder. And the reason for that is in most studies, and there have been a number of placebo controlled studies of individuals with borderline personality disorder, but in most of those studies, the individuals with bipolar disorder are excluded. So therefore, there's no data.

Similarly in many, I wouldn't say most, but in many studies, placebo controlled studies of bipolar disorder, individuals with borderline personality disorder are excluded. So there's very minimal, at best, controlled data. And given the significant psychosocial morbidity associated with the combination of the two disorders, the increased impairment in work functioning, the increased risk of suicidal ideation and suicidal behavior, it really is a shame that little attention has been paid to individuals with both of these two disorders occurring at the same time.

Thistle: So you went into this again a bit, but since there isn't a lot of research out there and there is a lot of gaps, what would you like your colleagues to know about borderpolar and correctly diagnosing? I know it's not diagnosis, it's a term, but if you want to go into that clarification as well a bit more, what do you want them to know about diagnosing borderpolar?

Dr Zimmerman: Again, we're not going to say diagnosing borderpolar. I'm sorry to correct you here, Meagan, but we're not going to talk about diagnosing borderpolar. We're going to talk about improving the recognition of both when both are present, and more specifically improving the recognition of borderline personality disorder in individuals who have bipolar disorder, keeping in mind that somewhere on the order of 20% of individuals with bipolar disorder also have borderline personality disorder.

How do you improve that recognition? Well, in the same way that you would improve the recognition of other disorders that are comorbid with bipolar disorder. You would screen for alcohol or other substance use disorders. You would screen for anxiety disorders that are frequently co-occurring with bipolar disorder. And likewise, you can screen for borderline personality disorder.

Now, borderline personality disorder has nine diagnostic criteria, and it's somewhat time consuming to ask about all of those diagnostic criteria. However, we did some research and published a few years ago on what would be the optimal screen. I don't mean a self-report screening questionnaire, but in the context of conducting your psychiatric evaluation, is there a criterion that you can inquire about that would help you recognize almost all individuals with borderline personality disorder?

And if that criterion wasn't present, it would effectively rule out the disorder, so you wouldn't have to ask about the other diagnostic criteria. We in fact found that one of the criteria had over a 90% sensitivity, in fact, it was about 93%, and a 99% negative predictive value. Meaning if this criterion, if this feature was not present, then the odds of the person having borderline personality disorder was practically zero. And that criterion was the affective instability criterion of borderline personality disorder.

Now someone may say, "Well, but isn't bipolar disorder associated with affective instability?" And sure, bipolar disorder is a mood disorder. There's affective instability, but it's different than the affective instability of borderline personality disorder, which is much briefer. The mood episodes of bipolar disorder are sustained. So when someone comes to me and says that they are a rapidly cycling bipolar disorder, that's what they have, meaning their mood shifts during the course of the day or from day to day, they may well have bipolar disorder, but that's more a characteristic feature of borderline personality disorder rather than ultra rapid cycling bipolar disorder.

And sure enough, if you then ask about the other diagnostic criteria for borderline personality disorder, it becomes clearer that that so-called ultra rapid cycling that individuals are referring to really is more consistent with their longstanding personality characteristics that are found with borderline personality disorder.

So, screening, to be brief, screening is the way to improve recognition, as it would be for other comorbid disorders.

Thistle: I really want to thank you for clarifying that it is a term, not a diagnosis. I think that's going to be really important for our audience of clinicians and to take that back into their practice. Is there anything else that you'd like to share before we sign off?

Dr Zimmerman: No, I think we've hit the highlights. The highlights being that it's important to recognize that with respect to borderline personality disorder and bipolar disorder, it's not an either/or selection or choice that needs to be made, that a not insignificant number of individuals have both disorders, and that when both disorders are found to be present, it's important to treat both pharmacologically and psychotherapeutically.

Thistle: Well, thank you so much again, Dr Zimmerman. It's always a pleasure. Looking forward to having you back. If you would like more information on this, please visit our Center of Excellence on Bipolar Disorder, as well as all of our market resource centers and excellence centers that can provide you with more information.

Dr Zimmerman: Well, thank you very much for having me, Meagan, and for allowing me to discuss this with your audience.

Thistle: Thank you.

Mark Zimmerman, MD, is a Professor of Psychiatry and Human Behavior at Brown University and director of the Partial Hospital Program and Outpatient Practice at Rhode Island Hospital. Dr Zimmerman is principal investigator of the Rhode Island Methods to Improve Diagnostic Assessment and Services (MIDAS) project. The MIDAS project has been ongoing for more than 25 years. The goal of the MIDAS project has been to integrate research methodology into routine clinical practice in order to improve clinical practice. 

Dr Zimmerman is the author of more than 450 articles published in peer-reviewed journals, and serves on the editorial board of 10 journals. He is the associate editor of the Journal of Personality Disorders. He has developed several measures of psychiatric disorders for use in clinical practice. He is the author of the Interview Guide to Diagnose DSM-5 Psychiatric Disorders and the Mental Status Examination.